Sign up to receive free email alerts when patent applications with chosen keywords are publishedSIGN UP

Abstract:

A motor vehicle light comprising an equipped flexible electronic support
that comprises: a flat flexible insulating support equipped on a first
face with a plurality of flat conductive tracks; at least one light
source of the light emitting diode type disposed on the first face of the
flexible insulating support; wherein a second face of the flexible
insulating support is covered with a layer of thermally conductive
material for dissipating the heat produced by the light emitting diodes,
the layer comprising an area of contact with the diode and an extended
area extending out of this contact area, the dissipation of the heat
taking place essentially at this extended area.

Claims:

1. An equipped flexible electronic support of the equipped "flexboard"
type, for a motor vehicle light, said equipped electronic support
comprising:a flat flexible insulating support equipped on a first face
with a plurality of flat conductive tracks;at least one light source of a
light emitting diode disposed on said first face of said flat flexible
insulating support, and connected to at least one of said plurality of
flat conductive tracks;wherein a second face of said flat flexible
insulating support is at least partially covered with a layer of
thermally conductive material for dissipating heat produced by said light
emitting diode, said layer of thermally conductive material comprising a
contact area at a connection between said light emitting diode and said
equipped flexible electronic support, and at least one extended area
extending out of said contact area, said layer of thermally conductive
material at least partially covering said second face of said flat
flexible insulating support at said at least one extended area, the
dissipation of heat taking place essentially at said at least one
extended area.

2. The equipped flexible electronic support according to claim 1, wherein
each of said light emitting diode disposed on said first face of said
flat flexible insulating support is associated with a stiffening element
disposed at said light emitting diode with which it is associated on said
second face of said flat flexible insulating support.

3. The equipped flexible electronic support according claim 2, wherein
said stiffening element has at least one opening intended to receive a
fixing pin, said fixing pin belonging to a three-dimensional optical part
on which said equipped flexible electronic support is placed.

4. The equipped flexible electronic support according to claim 3, wherein
said at least one opening in said stiffening element has a plurality of
retention tongues for holding, after deformation, said fixing pin that is
intended for it.

5. The equipped flexible electronic support according to claim 1, wherein
said layer of thermally conductive material covers the majority,
preferably the whole, of said second face of said flat flexible
insulating support.

6. The equipped flexible electronic support according to claim 1, wherein
a thickness and material constituting said layer of thermally conductive
material are chosen so that said layer of thermally conductive material
is plastic.

7. The equipped flexible electronic support according to claim 1, wherein
said layer of thermally conductive material has a thickness of less than
2 millimetres.

8. The equipped flexible electronic support according to claim 1, wherein
said layer of thermally conductive material has a thickness of less than
or equal to 75 microns.

9. The equipped flexible electronic support according to claim 2, wherein
said stiffening element and/or said layer of thermally conductive
material is/are made from copper.

10. The equipped flexible electronic support according to claim 1, wherein
said light emitting diode is of a power light emitting diode type.

11. The equipped flexible electronic support according to claim 1, wherein
said equipped flexible electronic support comprises several light
emitting diodes and several extended areas extending between each of said
light emitting diodes.

13. The vehicle headlight according to claim 12, wherein said equipped
flexible support has a three-dimensional arrangement having several
inflection points and said equipped flexible support comprises several
light emitting diodes with the inflection points being situated between
some or all of said light emitting diodes.

14. An equipped flexible electronic support of the equipped "flexboard"
type, for a motor vehicle light, said equipped electronic support
comprising:a flexible insulating support equipped on a first face with a
plurality of conductive tracks;at least one light emitting diode disposed
on said first face of said flexible insulating support, and connected to
at least one of said plurality of conductive tracks;wherein a second face
of said flexible insulating support is at least partially covered with a
layer of thermally conductive material for dissipating heat produced by
said at least one light emitting diode, said layer of thermally
conductive material comprising a contact area at a connection between
said at least one light emitting diode and said equipped flexible
electronic support, and at least one extended area extending out of said
contact area, said layer of thermally conductive material at least
partially covering said second face of said flexible insulating support
at said at least one extended area, the dissipation of heat taking place
essentially at said at least one extended area.

15. The equipped flexible electronic support according to claim 14,
wherein said at least one light emitting diode is disposed on said first
face of said flexible insulating support is associated with a stiffening
element disposed at said light emitting diode with which it is associated
on said second face of said flexible insulating support.

16. The equipped flexible electronic support according claim 15, wherein
said stiffening element has at least one opening intended to receive a
fixing pin, said fixing pin belonging to a three-dimensional optical part
on which said equipped flexible electronic support is placed.

17. The equipped flexible electronic support according to claim 16,
wherein said at least one opening in said stiffening element has a
plurality of retention tongues for holding, after deformation, said
fixing pin that is intended for it.

18. The equipped flexible electronic support according to 14, wherein said
layer of thermally conductive material has a thickness of less than 2
millimetres.

19. The equipped flexible electronic support according to claim 18,
wherein said layer of thermally conductive material has a thickness of
less than or equal to 75 microns.

20. A method of manufacturing an equipped flexible electronic support,
comprising the steps of:covering a second face of an insulating support
of a flexible electronic support with a thin layer of thermally
conductive material, a first face of said insulating support being
equipped with a plurality of conductive tracks;placing at least one light
emitting diode on each side of said flexible electronic support,
connected to at least one of said plurality of conductive tracks, and an
associated flat stiffening element, said flat stiffening element having a
thickness of between about 0.5 millimeters to about 5 millimeters;
andperforming a brazing operating by refusion in order to fix said at
least one light emitting diode to said flexible electronic support.

Description:

BACKGROUND OF THE INVENTION

[0001]1. Field of the Invention

[0002]This invention relates to motor vehicle lights and more particularly
to a flexible support for supporting at least one light emitting diode.

[0003]So-called conventional printed circuits have an insulating support
consisting of a resin plate that has a certain flexibility, in the sense
that it can be curved or arched by exerting a force on each side of the
circuit. However, the deformation of the resin plate is limited to one or
even two inflection points and the curvature cannot be too pronounced. In
addition, these plates are resilient and it is difficult to keep them in
a deformed configuration.

[0004]The field of the invention is, in general terms, that of motor
vehicle headlights. In this field, various types of headlight are known,
among which there are essentially: [0005]side lights, with low
intensity and range; [0006]passing or low beams, with higher intensity
and a range on the road of around 70 meters; [0007]long-range high beams,
and supplementary lights of the long-range type, whose area of vision on
the road is around 200 meters; [0008]improved headlights, referred to as
dual function, which combine the functions of low beams and high beams by
incorporating a movable shade; [0009]fog lights; [0010]signalling lights;
[0011]signalling devices for daytime use, referred to a DRL lights
(standing for daytime running lights in English) etc.

[0012]For all these lights, traditionally, light sources of the halogen
lamp or discharge lamp type are used. However, for a few years now,
automotive equipment manufacturers have proposed the use of light
emitting diodes; this use initially concerned essentially indicator
lights or rear lights, but an increase in the power available in LEDs now
makes it possible to envisage new uses of these light sources, in
particular for performing the light functions present at the front of the
vehicle, and more precisely the DRL and side light functions. Light
emitting diodes allowing the performance of this type of function are
designated as power LEDs. A power LED is more generally an LED making it
possible, alone or in association with other LEDs, to perform lighting
functions other than signalling functions and the function associated
with signalling devices disposed at the rear of the vehicle. A power LED
generally has a light flux of around at least 30 lumens.

[0013]Light emitting diodes have a certain number of advantages:
[0014]first of all, for a long time, it has been known that this type of
diode does not radiate directionally but radiates in a half-space
opposite to a substrate that supports the p-n junction of the diode in
question; thus, by using a more directional radiation than the halogen or
discharge lamps of the prior art, the quantity of energy lost is less
than with discharge or halogen lamps; [0015]next, these diodes have
recently been improved in terms of radiation power intensity. In
addition, the diodes manufactured have long been emitting radiation in
the red range, but now also in the white range, which increases the field
of their uses that can be envisaged. With regard to the LEDs used in
signalling, the quantity of heat that they give off is relatively
limited, and a certain number of constraints, relating to the dissipation
of the heat in the headlight devices of the prior art, disappear; the
problem of heat dissipation does however remain significant for power
LEDs; [0016]finally, diodes consume less energy, even at an equal
intensity of radiation, than discharge lamps or halogen lamps; they are
compact, and their particular shape offers novel possibilities for
producing and arranging complex surfaces that are associated with them,
in particular by disposing them on electronic supports of the flexible
electronic support type.

[0017]More and more, in particular to meet aesthetic criteria required by
motor manufacturers, it is sought to dispose three-dimensionally, within
the same headlight device, several light emitting diodes: within a given
lighting device, various LEDs, possibly different types, are disposed on
different support planes; in other words, a three-dimensional optical
piece can now be intended to receive and hold a plurality of light
sources in different planes.

[0018]The existing solutions for such juxtapositions initially consisted,
in the case of LEDs, essentially of using rigid electronic supports,
known to persons skilled in the art, of the CEM1, FR4, SMI or MCPCB
substrate type or the like for supporting the various light sources. The
use of rigid electronic supports has in particular a high manufacturing
cost and drawbacks in terms of interconnection of the different
substrates.

[0019]2. Description of the Related Art

[0020]In the prior art, a particular solution has recently been proposed
for effecting a placing of light emitting diodes in a three-dimensional
environment. Thus the patent FR 2881274 describes a flexible electronic
support equipped with LEDs allowing a simplified assembling on a
reflector comprising several LED support planes. Radiator elements are
assembled on a first face of the flexboard. The LEDs are fixed to a
second face of the flexboard, each LED being positioned so that a
radiator element is associated with it directly on each side of the
flexboard. Each radiator element comprises openings intended to receive a
fixing pin pointing at a rear face of the reflector. This makes it
possible to assemble the equipped flexboard and the reflector in a simple
and precise manner by introducing one of the fixing pins of the reflector
into each opening.

[0021]However, the current use of power LEDs makes it necessary to further
improve the discharge of heat at the LEDs.

[0022]What is needed, therefore, is a system, flexible support and method
that overcomes one or more of the problems of the prior art.

SUMMARY OF THE INVENTION

[0023]The aim of the invention is therefore to find a device integrating
an equipped support that makes it possible to further discharge the heat
emitted by LEDs and in particular power LEDs.

[0024]The object of the present invention is an equipped electronic
support supporting at least one light emitting diode, or LED, and more
particularly an equipped flexible electronic support of the equipped
"flexboard" type supporting at least one LED.

[0025]The expression "flexible electronic support", also designated by the
expression flexible printed circuit, or the English term "flexboard",
means an assembly constituted by an electrically insulating support,
flexible and planar--also designated as a flexible insulating
support--and flat metal conductors intended to provide electrical
connections between electronic components that will be disposed at the
surface of the said support.

[0026]The flexible electronic supports as defined in the present
application are distinguished from the other printed circuits by the fact
that, instead of a resin plate, the insulating support is a flexible
insulating support thus making it possible to confer on the flexible
electronic support orientations and forms with almost as much freedom as
with a tape or a sheet. These flexible electronic supports can thus
easily be adapted to complex three-dimensional configurations having many
angles or inflection points. This type of flexible electronic support is
for example used in the device disclosed by the patent FR 2881274.

[0028]The aim of the invention is essentially to propose a solution for
equipping a three-dimensional optical piece--for example a reflector, a
screen, a mask, or any part able to serve as a fixing piece within a
motor vehicle headlight module--with light sources of the LED type, the
solution being compact and in particular meeting significant constraints
in terms of the dissipation of heat generated by the LEDs.

[0029]The use of flexible electronic supports is advantageous because of
their flexible character: they can be bent easily in order to place them
three-dimensionally on an optical part of any shape. Another important
advantage of flexible electronic supports lies in the fact that they
require no connection system for interconnection between different
electronic cards, affording a saving in labor, making the assembly
reliable and reducing the overall size compared with the solutions
involving rigid supports.

[0030]The object of the invention proposes a solution meeting the heat
dissipation constraints of flexboards equipped with LEDs, in particular
power LEDs, whilst having minimum bulk. To this end, it is proposed in
the invention to associate a layer of thermally conductive material on
the face of the flexboard opposite to the face supporting the light
emitting diodes. Thermally conductive material means here a material
having a satisfactory dissipation capacity, sufficient to discharge all
the calories produced by the LEDs.

[0031]Advantageously, in the invention, each LED is associated with a
stiffening element providing rigid holding for the LED in question,
facilitating the operation of manufacturing the equipped flexboard.

[0032]The invention therefore concerns essentially an equipped electronic
support for a motor vehicle light, the equipped electronic support
comprising in particular: [0033]a flat flexible insulating support
equipped on a first face with plurality of flat conductive tracks;
[0034]at least one light source of the light emitting diode type disposed
on the first face of the flexible insulating support and connected to at
least one of the flat conductive tracks;

[0035]a second face of the flexible insulating support being covered at
least partially by a layer of thermally conductive material for
dissipating the heat produced by the light emitting diodes, the layer
comprising a contact area at the connection between the diode and the
equipped electronic support, and an extended area extending out of this
contact area, the dissipation of the heat taking place essentially at
this extended area.

[0036]More particular, the invention concerns an equipped flexible
electronic support, of the equipped "flexboard" type, for a motor vehicle
light, the equipped electronic support comprising: [0037]a flat
flexible insulating support equipped on a first face with plurality of
flat conductive tracks; [0038]at least one light source of the light
emitting diode type disposed on the first face of the flexible insulating
support and connected to at least one of the flat conductive tracks;

[0039]a second face of the flexible insulating support is covered at least
partially by a layer of thermally conductive material for dissipating the
heat produced by the light emitting diodes, the layer comprising a
contact area at the connection between the light emitting diode and the
equipped flexible electronic support, and at least one extended area
extending out of this contact area, the layer of thermally conductive
material at least partially covering the second face of the flexible
insulating support at the extended area, the dissipation of the heat
taking place essentially at this extended area.

[0040]The equipped flexible electronic support according to the invention
can comprise, in addition to the main characteristics that have just been
mentioned in the previous paragraph, one or more additional
characteristics from the following: [0041]each light emitting diode
disposed on the first face of the flexible insulating support is
associated with a stiffening element disposed at the diode with which it
is associated on the second face of the flexible insulating support;
[0042]the stiffening element has at least one opening intended to receive
a fixing pin, the fixing pin belonging to a three-dimensional optical
part on which the equipped flexible electronic support is placed;

[0043]the stiffening elements have at least one area forming a projection;

[0044]the opening in the stiffening element has a plurality of retention
tongues for holding, after deformation, the fixing pin that is intended
for it; [0045]a layer of adhesive with an exclusive holding function is
disposed, on the flexible insulating support at each stiffener, in
contact with each stiffener; [0046]the layer of thermally conductive
material covers the majority, preferably the whole, of the second face of
the flexible insulating support; [0047]the thickness and the material
constituting the layer of thermally conductive material are chosen so
that the layer of thermally conductive material is plastic; the equipped
flexible electronic support according to the present invention is thus
malleable and it is possible to confer varied three-dimensional shapes on
it, able to have many inflection points and large changes of direction,
for example angles or curvatures greater than 45 degrees. With a certain
thickness, chosen according to the material, it is possible to have a
manual deformation of the equipped flexible electronic support according
to the chosen shape, before mounting, this shape being kept by the
support. For example, it is possible to use a sheet of pliable copper,
for example, 1 millimeter thick; [0048]the layer of thermally conductive
material has a thickness of less than or equal to 75 microns; [0049]at
least two stiffeners are joined together made in one piece, so that the
metal part situated between the contact areas of the stiffeners
constitutes the extended area; [0050]stiffener comprises fins for
increasing the heat-dissipation surface; [0051]the stiffening element
and/or the layer of thermally conductive material is/are made from
copper; [0052]the light emitting diodes are of the power light emitting
diode type; [0053]the equipped flexible electronic support comprises
several light emitting diodes and several extended areas extending
between each light emitting diode.

[0054]The present invention also relates to a motor vehicle light
comprising an equipped electronic support according to the present
invention. Preferentially the equipped flexible support of this light has
a three-dimensional arrangement having several inflection points and the
flexible support comprises several light emitting diodes, the inflection
points being situated between some or all of the light emitting diodes.
Preferably there is at least one inflection point between each light
emitting diode.

[0055]The present invention also relates to a method of manufacturing the
equipped flexible electronic support according to the invention,
comprising at least the main characteristics, and possibly one or more of
the additional characteristics mentioned, the method comprising the
various steps of: [0056]covering a second face of the flat insulating
support of a flexible electronic support with a thin layer of thermally
conductive material, a first face of the insulating support being
equipped with a plurality of conductive tracks; [0057]placing at least
one light emitting diode on each side of the flexible electronic support,
connected to at least one of the conductive tracks, and an associated
flat stiffening element, the stiffening element having a thickness of
between 0.5 millimeters and 5 millimeters; [0058]then performing a
brazing operating by refusion in order to fix the light emitting diodes
to the flexible electronic support.

[0059]In a particular embodiment of the invention, the step of placing the
stiffening element comprises the prior operation consisting of disposing
an adhesive with the sole function of holding on the thin layer of
thermally conductive material at the stiffening element.

[0060]Another object of the invention lies in the use of the equipped
flexible electronic support according to the invention, comprising at
least the main characteristics and possible one or more of the additional
characteristics mentioned, in a motor vehicle light device of the DRL
type.

[0061]In the various embodiments according to the present invention, the
flexboard supports and connects the LED electrically. The layer of
thermally conductive material dissipates the heat emitted by the LED.
Preferentially, the stiffener makes it possible to protect the connection
of the LED on the flexboard, to ensure the precision of its positioning
in relation to the lens and to fix the LED plus flexboard assembly to the
lens, by clamping, by a gripping means or by riveting by means of
ultrasound, or any other plastic deformation.

[0062]These and other objects and advantages of the invention will be
apparent from the following description, the accompanying drawings and
the appended claims.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

[0063]The invention and its various applications will be understood better
from a reading of the following description and an examination of the
figures that accompany it.

[0064]They are presented only by way indication and are in no way
limitative of the invention. The figures show:

[0065]FIG. 1, already described, is a schematic representation of an
example embodiment of an equipped flexible electronic circuit of the
prior art;

[0066]FIG. 2, also already described, is a schematic representation of a
cross-section through the example embodiment in FIG. 1;

[0067]FIG. 3 is a schematic representation of an example embodiment of an
equipped flexible electronic circuit according to a particularly
advantageous embodiment of the invention;

[0068]FIG. 4 is a schematic representation of a cross-section through the
example embodiment in FIG. 3;

[0069]FIG. 5 is an example of means of fixing the flexible electronic
circuit according to the invention on an optical piece.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0070]The various elements appearing in several figures will, unless
specified to the contrary, have kept the same reference.

[0071]FIG. 1 depicts schematically a cross-section through an optical
element 105 intended to be positioned in a lighting device, the optical
element 105 resulting from the fixing to a reflector 102 of a flexible
electronic support or flexboard 100, equipped, on a first face 106, with
light emitting diodes or LEDs 101; the reflector 102 constitutes a
three-dimensional environment, since it comprises several support planes
for light sources.

[0072]Stiffening elements 103 are disposed on a second face 107 of the
flexboard 100 at each light emitting diode 101; thus pluralities of
diode/stiffener pairs are formed, the two elements of the pairs being
disposed on each side of the flexboard 100 while being separated only by
the flexible insulating support 202 constituting in this example the
flexboard 100. In other words, the position of each LED 101 is
approximately centered on the position of the stiffening element 103 that
is associated with it. In the manufacture of each stiffening element 103,
provision is made for forming openings, including at least one first
opening 500 intended to receive a fixing pin 104 pointing at a rear face
of the reflector 102 in order to ensure the fixing of each stiffening
element 103 to the flexboard 100.

[0073]As shown in FIG. 2, a flexboard 100a, here shown in cross-section,
consists of a flexible insulating support 202--composed in a known
fashion of layers of different materials--on which there are disposed
electrically conductive tracks 203 covered with an electrically
insulating material 205, must be supplemented by a layer 201 of adhesive
204 intended to provide the heat transfer and the mechanical holding of
the stiffening element 103 on its body. The adhesive chosen for the layer
201 of adhesive 204 must have high heat conduction characteristics in
order to best transmit the heat given off by the LED 101 at the
stiffening element 103.

[0074]The stiffening element 103 comprises, on each side of its body, heat
dissipation fins 200 perpendicular to the body of the stiffening element
103 in contact with the flexboard 100. This is a non-limitative example.
The fins 200 could for example make another angle with the body of the
stiffening element 103. The radiator elements can consist of a simple
metal plate, bent in order to constitute the fins 200. Other thermally
conductive materials can however be envisaged. Different techniques can
also be used for obtaining the radiator elements with fins 200, such as
molding, extrusion or machining techniques.

[0075]As shown, the body of the stiffening element 103 therefore
constitutes the layer of thermally conductive material covering the
second face of the flexible insulating support 202, and also the contact
area at the connection between the LED 101 and the equipped flexible
electronic support 100. The heat emitted by the LED 101 is transmitted
via this contact area directly to the extended areas, formed by the fins
200. The heat is dissipated essentially at these extended areas.

[0076]Such a device has heat dissipation properties appreciably improved
compared with the prior art, while having the following advantages:
[0077]photometric advantage because the light emitting diodes are mounted
directly on the optical piece; the position of each LED 101 with respect
to the part of the reflector 102 where it must be placed is thus more
precise, each LED 101 being associated with an independent stiffening
element 103; each LED 101 thus keeps freedom of movement that makes it
possible to recenter it individually, without causing any movement for
the other LEDs 101; [0078]financial advantage because of the reduction in
the number of LEDs 101 necessary for obtaining a given flux, by virtue of
an optimization of the placing of each of the LEDs 101 within the
reflector 102.

[0079]However, the stiffening elements 103 are bulky, in particular
because of the presence of fins 200. This bulk is detrimental since it
results in an increase in the volume of final product in which the
flexboard 100 will be installed. Apart from the space requirement in the
final product the presence of the fins 200 makes it necessary to assemble
the stiffening elements 103 on the flexboard 100 after an operation of
brazing by re-fusion of the flexboard 100 equipped with the LEDs 101, the
thickness of the lugs preventing from placing the stiffening elements 103
on the plates involved in such brazing operations. The process of
manufacturing the equipped flexboard 100 is thus made more complex.

[0080]According to another embodiment, not shown, at least two stiffening
elements 103 are produced in one piece. For example, these two stiffening
elements 103 are produced from the same sheet of conductive material. In
such a case, the portion of the sheet that will connect the area where
the stiffening element 103 is in contact with the flexboard 100 at the
LED 101 constitutes an area extended out of the contact areas, by means
of which the heat is dissipated. The same type of adhesive as previously
mentioned is used. According to a variant embodiment, all the stiffening
elements 103 are formed from a single sheet. In such case, it is
necessary to confer on the sheet a shape enabling each contact area to
come into contact with an LED 101.

[0081]Although less bulky, such a system is not very adaptable since the
equipped flexible electronic support 100 does not have a flexible portion
between some LEDs 101. In the extreme case where the assembly is formed
by a single sheet, the support can be adapted only to a precise
three-dimensional environment and therefore to a given light.

[0082]In addition, in the two aforementioned embodiments, the thermally
conductive adhesive used is particularly expensive.

[0083]A particularly advantageous embodiment of the present invention,
shown in FIGS. 3 and 4, makes it possible to mitigate these drawbacks.

[0084]In the example shown in FIG. 3, a flexible electronic support or
flexboard 300 equipped according to the invention is put in place in an
environment similar to the one in FIG. 1: thus the optical element 105
shown in section, the light emitting diodes 101, the reflector 102 and
the fixing pins 104 are found again in FIG. 3.

[0085]The flexboard 300 is also detailed with reference to FIG. 4 in a
view in section. The flexboard 300 consists of a flexible insulating
support 302, on a first face 306 of which conductive tracks 303 serving
for supplying the LEDs 101 are disposed. The conductive tracks 303 are
covered with an insulating material 309. A second face 307 of the
flexible insulating support 302 is covered with a thin layer 301 of
thermally conductive material, or heat-dissipating material. A layer of
adhesive 304 is used in this example for holding the thin layer 301.

[0086]The thin layer 301 can be produced from any material having good
heat dissipation capabilities, for example copper, aluminum, stainless
steel or various copper-based alloys, but also materials based on
graphite. The thin layer 301 is not produced from a material of the
adhesive type. To obtain optimum heat dissipation, the thickness of the
thin layer 301 is preferably of less than 2 millimeters, advantageously
between 60 microns and 90 microns, conclusive tests having been carried
out with a thickness of 75 microns. Preferentially, the thickness is less
than or equal to 75 microns, and particularly between 60 microns and 75
microns.

[0087]The thin layer 301 constitutes the layer of thermally conductive
materials covering the flexible insulating support 302 according to the
present invention. The area situated at the connection between the LED
101 and the equipped flexible electronic support 300 constitutes the
contact area. The portion of thin layer 301 that connects each contact
area constitutes an area extended outside the contact areas, for which
the heat is dissipated. The thin layer 301 being flexible through its
thickness and through the material making it up, the equipped electronic
support 300 is therefore flexible.

[0088]Advantageously, the thin layer 301 covers all the second face 307 of
the flexible insulating support 302, thus greatly improving the
dissipation of the heat produced by the LEDs 101.

[0089]In a particular example embodiment, stiffening elements 305 which
consist of a rigid plate, for example metal, and which are placed
vertically in line with each light emitting diode 101, are disposed on
the same side as the second face 307 and above the thin layer 301. Their
function is in particular to ensure the holding of the light emitting
diodes 101 when they are disposed on the flexboard 300, but also during
operations of mounting on the optical pieces of the reflector type.

[0090]The presence of the thin layer 301 and its capacity to dissipate the
heat produced by the LEDs 101 makes it possible to use stiffening
elements 305 without fins. The heat exchange is essentially effected at
the thin layer 301 situated between two stiffening elements 305. A
substantial gain in thickness of the equipped flexboard 300 is thus
achieved compared with the embodiment depicted in FIGS. 1 and 2.

[0091]The stiffening elements 305 are advantageously held on the thin
layer 301 by an adhesive having solely properties of mechanical strength;
the stiffening elements 305 do not serve as a radiator and it is not
therefore necessary to use an adhesive--more expensive--having good heat
exchange characteristics. The thickness of the stiffening elements 305 is
around 0.5 to 3 millimeters. They may, in order to increase their rigid
character, have an area forming a projection 308, for example in the form
of a protrusion extending along the entire side of the stiffening element
305. Even with the area forming a projection, the stiffeners do not
exceed 5 millimeters in thickness.

[0092]In all cases, whether or not there are stiffeners present, the
equipped flexboard 300 according to the invention can be totally equipped
before undergoing brazing operations by re-fusion intended essentially to
solder the LEDs 101 to the flexboard 300. This is because no element is
too bulky to be disposed on the plates taking part in such brazing
operations by re-fusion.

[0093]It should be noted that, in the case where the size constraints in
the light where the equipped flexible electronic support 300 is to be
mounted are not high, it is always possible to use a stiffening element
305 with fins in addition to the thin layer 301, in order to increase
even further the heat dissipation capacity. However, since the thin layer
301 gives sufficient heat dissipation, it is generally preferred to
reduce the size of the equipped electronic flexible support 300.

[0094]Fixing pins 104 are intended to be introduced into openings in the
stiffening element 305, passing through the flexboard 300 pierced for
this purpose.

[0095]FIG. 5 shows two examples of openings provided in the stiffening
element 305. These examples of openings can be applied to the various
stiffening elements 103 or 305 of various embodiments according to the
present invention, in particular those depicted in FIGS. 1 and 3. In the
first example of an opening 500 and a second example of an opening 502,
each opening is intended to receive a fixing pin 104 pointing at a rear
face of the reflector 102. It is then possible to proceed with the
assembly of the equipped flexboard 300 and the reflector 102 by
introducing one of the fixing pins 104 of the reflector 102 into each
opening. A supplementary clipping operation between the equipped
flexboard 300 and the reflector 102 can then be carried out in order to
ensure the definitive holding between the elements.

[0096]In an advantageous embodiment, namely the first example, the first
opening 500 is characterized by a roughly circular shape, with a
periphery having a plurality of retention tongues 501. Each retention
tongue 501 is characterized by a base, directly attached to the
stiffening element 305, and by a free end, oriented towards the central
part of the first opening 500. Such an opening thus constitutes a
clamping means or a means for gripping. It should be noted that such a
means can also be produced by an opening having a single retention tongue
503 as is the case with the second opening 502, in the second example.

[0097]When one of the fixing pins 104 is introduced into the openings 500
and/or 502, each retention tongue 501 and/or 503 can slightly deform in
the direction of the introduction movement, the free ends of each
retention tongue 501 then accompanying the fixing pin 104 in its change.
The plurality of retention tongues 501 of the first opening 500 make it
possible best to hold the fixing pin 104 in the first opening 500: the
elastic character of the material employed to produce the stiffening
element 305, and therefore to produce the retention tongues 501, has this
advantage of interfering with a movement that is the reverse of the
movement of introducing the fixing pin 104 into the first opening 500.

[0098]The main function of the second opening 502 is to receive one of the
fixing pins 104 in order to prevent any rotation of the stiffening
element 305. In practice, provision is made for each light emitting diode
101 to be associated with two fixing pins 104. The flexboard 300 then has
a number of openings equal to twice the number of LEDs 101.

[0099]The stiffening elements 305 are then preferably produced from a
ductile material, for example copper. Two openings per stiffening element
305 prevent any rotation of the stiffening elements 305 during operations
of mounting the equipped flexible electronic supports 300 according the
invention.

[0100]Other fixing methods, based on ultrasound for crushing the fixing
pins 104 or snap riveting operations, can also be used to hold the
equipped flexboards 300 according to the invention on any optical
support.

[0101]While the method herein described, and the forms of apparatus for
carrying this method into effect, constitute preferred embodiments of
this invention, it is to be understood that the invention is not limited
to this precise method and forms of apparatus, and that changes may be
made in either without departing from the scope of the invention, which
is defined in the appended claims.

Patent applications by Vincent Biarne, Sevran FR

Patent applications by VALEO VISION

Patent applications in class Including specific light bulb mounting

Patent applications in all subclasses Including specific light bulb mounting